Method of making finished metal die castings

ABSTRACT

A method of making a finished metal die casting, especially one formed of aluminum or zinc, or alloys thereof, and having one or more well portions, the outer surfaces of which are to be buffed prior to plating. The method involves taking a die casting, from which unwanted metal, in the form of flashing remaining on the edges of the walls of the casting after it has been removed from the mold, or in the form of a bead remaining at the edges of the walls of the casting after the flashing has been removed in accordance with standard practices, and rigidly positioning the die casting with support means with the outer surfaces of the walls of the casting facing outwardly and the unwanted metal bearing edges of the walls extending to a point where they are free of contact with the support means. With the casting so positioned, a metal shearing or cutting tool is moved outwardly from the inner side of the walls of the casting to sever the walls at a point inwardly of the edges thereof to form new edges on the walls having metal burrs therealong adjacent to the outer surface of the walls. The casting is then removed from the support means, and the outer surfaces of the walls are buffed to simultaneously impart a finished appearance to the casting and to remove the burrs from the newly formed edges. Other operations, such as piercing holes in the casting, can be performed at the same time as the walls are being sheared or trimmed.

United States Patent 1191 Foster 1451 July 31,1973

METHOD OF MAKING FINISHED METAL DIE CASTINGS [5 7] ABSTRACT A method of making a finished metal die casting, especially one formed of aluminum or zinc, or alloys [75] lnventor: Edwin T. Foster, South Haven, 1 r .1

Mich thereof, and having one or more wall portions, the outer surfaces of which are to be buffed prior to plat- [73] Asslgnee: Du'WeI f Products -1 ing. The method involves taking a die casting, from Bangor, Mlchwhich unwanted metal, in the form of flashing remain- [22] Filed: Oct 14, 1971 ing on the edges of the walls of the casting after it has been removed from the mold, or in the form of a bead [2]] pp No.2 189,184 remaining at the edges of the walls of the casting after the flashing has been removed in accordance with stan- 52 us. 01 51/323, 51/5, 83/191, dard Practices and rigidly P "8 the die casting 83/518 83/914 with support means with the outer surfaces of the walls 51 1 lm. c1 B24b 1/00 Ofthe casting facing outwardly and the unwanted metal [58] Field of Search 51/5, 323, 324; bearing edges of the Walls extending a P Where 29/5216; 164/76; 83/185 186 190 191 they are free of contact with the support means. With 914, 54, 518 the casting so positioned, a metal shearing or cutting tool is moved outwardly from the inner side of the walls 5 References Cited of the casting to sever the walls at a point imlvaLdly of the edges thereof to form new edges on t e wa ls aving UNITED STATES PATENTS metal burrs therealong adjacent to the outer surface of g gf g the walls. The casting is then removed from the support 2001578 5/1935 i g?" 83/55 x means, and the outer surfaces of the walls are buffed to 3:383:966 5/1968 Widani::::::........... 1:11.... 83/185 smultanmusly 3 fin'shed appearance to the 3,633,322 1/1972 Morcom 51/5 x casting and remm'e the bum from the newly fomed edges. Other operations, such as piercing holes in the primary Examiner Donald Kelly casting can be performed at the same time as the walls Attorney-Wallenstein, Spangenberg, Hattis & are bemg sheared or Strampel 5 Claims, 7 Drawing Figures gwea "Kaim 22a lg PAIENIH; JUL 3 1 I975 3 a I 8 T l SHEET 1 OF 2 SEVER SIDEMZZJ lzvnmozraf aux-PING OUTER sum-ma a AMP DIE FLASH/N6 0/? 854.0 NAME slpfmus T0 s/MuLTA/vwwzr Sr/N6 IN 0y Mar/A16 SHEAR/N6 Peal 1054 FIN/8H 01v sn/o PLACE TOOL earn n00; r FROM sun/mass AND r0 REMO v:

THE INNER 5/05 OF THE am s REM/L TIA/6 FROM ms WALLS. SHEAR/N6 OPERATION.

FIG.

1 Fa G. 66 4e 58 48 Eu VEN?@ Eawnv 7. F05 TEE METHOD OF MAKING FINISHED METAL DIE CASTINGS The present invention relates to a method of making a finished die casting.

Die castings made from metals such as aluminum or zinc, or alloys thereof, have a substantial amount of excess metal extending outwardly from the edges of the walls of the casting when they are removed from the die casting mold. This excess metal, which is referred to in the trade as flashing, must be removed from the die casting before it can be finished. Heretofore, the removal of the flashing from the die casting was accomplished by positioning the die casting on a suitable support with the flashing extending outwardly in a substantially horizontal plane from the wall of the die casting, and then severing the flashing by moving a shearing or cutting tool downwardly in a vertical plane along the outer surface of the wall of the die casting. The trimming operation left an outwardly extending hump or bead along the edge of the wall of the die casting at the point where the flashing was removed. This bead not only detracted from the appearance of the die casting, but, also, exposed pores in the metal of which the die casting was formed. In accordance with prior practices,

the porous head was removed by a polishing or grinding operation which, however, still left a porous surface which produced a rough plated surface along the edge of the die casting which was tolerated but not desired. Moreover, the polishing operation was expensive and time consuming, especially in those instances where the die casting had flashing on two or more walls thereof, and, consequently, constituted a significant production cost factor in the making of finished die castings.

In accordance with one aspect of the present invention, a method is provided for making a finished die casting which completely eliminates the separate polishing or grinding operation, heretofore required in the manufacture of die castings made from aluminum or zinc, or alloys thereof, due to the manner in which the flashing is removed from the die castings. It is important to note that the elimination of the separate polishing or grinding operation required by prior practices is achieved with the method of this invention both when the flashing is left on the die casting after it is removed from the mold, and in those instances when, for some reason, the flashing has been removed from the die casting in accordance with prior practices and the porous bead still remains on thewall portions of the die casting. The method can be carried out with die castings of substantially any size and shape, and enables, with only a single positioning of the die casting, the removal of the flashing or porous bead, whichever is the case, from a die casting having a plurality of sides of walls each of which carries flashing, or a porous bead.

In accordance with another aspect of the present invention, the removal of the flashing or porous bead from a die casting can be carried out at the same time as other operations, such as hole piercing or punching, are being performed on the die casting. Here, again, only a single positioning of a die casting is required to achieve both the removal of the flashing or porous bead, and the piercing or punching of holes or the like in the die casting. The method of the present invention has further economic advantages in that it can he carried out with commerical equipment used primarily in trimming sheet metal stampings and with minimal operating personnel.

Briefly, the method of this invention involves the steps of stationarily positioning or anchoring, with suitable support means, a die casting having flashing or a porous bead resulting from the removal of the flashing along an edge of at least one side or wall of-the die casting. The die casting is positioned or anchored so that the outer surface of the said side or wall thereof is facing outwardly with relation to the support means and the flashing or porous bead bearing edge of the side or wall extends to a point where it is free of contact with the support means. The side or wall of the die casting is then severed along a line inwardly of, and substantially parallel to, the flashing or porous bead bearing edge of the side or wall of the die casting by moving a metal shearing or cutting tool outwardly from the inner surface of the side or wall of the casting to form a new edge on the side or wall of the casting having small burrs therealong adjacent to the outer surface of the side or wall. The flashing or porous bead having been thusly removed, the side or wall of the die casting is subjected to a buffing operation to simultaneously impart a finished appearance to it and to remove the burrs along the newly formed edge thereof. As indicated hereinabove, the flashing or porous bead can be removed from a multi-sided or walled die casting by successively moving the metal shearing or cutting tool outwardly from the inner surface of each side or wall to sever it as described to form a new edge on each side or wall having small, easily removed burrs therealong adjacent to the outer surface of each of the sides or walls. The outer surfaces of the sides or walls are then buffed as before to give them a finished appearance and to remove the burrs. Also, as indicated hereinabove, holes or the like, may be formed in the die casting at the same time as the flashing or porous bead removal operation is being performed. In this instance, the hole or the like forming tool advantageously completes its operation, and then acts as an anchoring or clamping means for the die casting while the flashing or porous bead removal operation is being carried out.

The foregoing and other features and advantages of the invention will be more fully understood from the following detailed description when read in conjunction with the accompanying drawing wherein:

FIG. 1 is a brief outline'of the steps involved in carrying out the method of the present invention in accordance with one of its aspects;

FIG. 2 is a view in perspective of an embodiment of a die casting, of the type used as the control panel for an automatic laundry unit, with the flashing removed from the sidewalls thereof and a porous bead remaining along the edges from which the flashing was trimmed;

FIG. 3 is a fragmentary vertical sectional view showing the die casting illustrated in FIG. 2 supported on apparatus suitable for carrying out the method of the present invention;

FIG. 4 is a fragmentary vertical sectional view taken at an angle of approximately to the sectional view shown in FIG. 3;

FIG. 5 is a view in perspective of the embodiment of the die casting illustrated in FIG. 2 after it has been removed from a mold with the flashing on the edges of the sidewalls thereof;

FIG. 6 is a fragmentary vertical sectional view showing the die casting illustrated in FIG. 5 supported on apparatus suitable for removing the flashing from, and forming holes in, the die casting in accordance with the method of this invention, with the section through the die casting being taken substantially along line 6-6 of FIG. and

FIG. 7 is a fragmentary vertical sectional view taken at approximately 90 to the view shown in FIG. 6, with the sectional through the die casting being taken substantially along line 7-7 of FIG. 5.

Referring, now, more specifically to FIGS. 2, 3 and 4 of the drawings, the die casting 10 illustrated in FIG. 2 is representative of a zinc or aluminum, or alloy thereof, die casting which can be finished in accordance with the practice of the present invention. The casting 10, as indicated, is of the type that may be used as a control panel for a home laundry unit, and, as shown, comprises a rectangularly shaped body 12 having a stepped front wall 14 formed of a rasied, control knob-receiving section 14a and a depressed, name plate section 14b. The body 12 has a rearwardly extending top wall 16 and a pair of rearwardly extending end walls 18-18 joined to the front wall 14 thereof. A longitudinally grooved pedestal portion 20 is joined to the body 12 along the lower longitudinal margin of the front wall 14 thereof, and, as shown is provided with a rearwardly extending bottom wall 22.

In the embodiment of the die casting 10 illustrated, the flashing has been removed from the outer edges of the top wall 16 and the end walls 18-18 of the body 12, and from the outer longitudinal edge of the bottom wall 22 of the pedestal portion 20, in accordance with conventional practices, that is, by vertically moving a metal shearing or cutting tool along the outer surface of the top wall 16, the end walls 18-18, and the bottom wall 22, into engagement with the horizontally extending flashing thereof, to sever the flashing. As a result of this trimming operation, outwardly extending humps, or porous beads 16a, 18a-18a, and 22a remain on the edges of the walls 16, 18-18, and 22, respectively. As stated hereinabove, prior practices required that the porous bead be removed by grinding before the die casting was buffed and plated. This grinding operation leaves an unwanted porous strip and is laborious and time consuming, especially with die castings such as the die casting l0, and, perforce, significantly increases the cost of finishing the die castings.

Slots 24-24, holes 26-26, and a control knob shaft opening 28 and its associated screw-receiving openings 30, are provided in the section 14a of the front wall 14 of the die casting 10.

The method of the present invention enables the complete elimination of the grinding operation, and, in accordance with a specific, preferred aspect thereof, enables the clean removal of the porous bead, or flashing, whichever is the case, and the formation of holes and slots in the front wall, in a single operation.

Referring, now, in particular, to FIGS. 3 and 4 of the drawings, the utilization of the method of this invention to remove the porous beads 16a, 18a-l8a and 220 from the walls of the die casting 10 in one operation is shown. As illustrated, the die casting 10 is cradled on a support unit or locater body 40, the upper surface of which is shaped to conform to the contours of the back of the front wall 14 of the die casting. The locater body 40, in turn, is supported on a stationary table 42. The porous bead-bearing edges of the top wall 16 and the end walls 18-18 of the body 12, and the bottom wall 22 of the pedestal portion 20, extend below the base of the table 42. A clamping force communicating holder member 44 conforming to the shape of portions of the front wall 14 of the die casting 10 is supported on the front wall 14 so that the die casting is sandwiched between the locator body 40 and the holder member 44. A vertically movable clamping head assembly46 is employed to hold or clamp the die casting 10 in a stationary position.

The clamping head assembly 46, as shown, comprises a mounting plate or head 48 on which two pairs of shearing or cutting die holders 50-50 and 52-52 are mounted. A pair of stationary metal shearing or cutting dies 54-54 are secured to the holders 50-50, while a second pair of stationary metal shearing or cutting dies 56-56 are secured to the holders 52-52. The positioning of the dies on the holders is such that the bottom wall of each of the dies extends slightly below the bottom wall of its associated holder, and the outer vertical surface of each of the dies, and a portion of the vertical inner surface of each of the holders is in contact with the outer surface of an opposed downwardly extending wall of the die casting 10. The head 48 has stops 58 secured to the undersurface thereof for exerting pressure on the holder member 44 when the assembly 46 is in its lowered position.

Shearing or cutting of the porous beads along the edges of the downwardly extending walls of the die casting 10 is achieved with the apparatus illustrated in FIGS. 3 and 4 by providing two pairs of movable shearing or cutting dies 54a-54a and 56a-56a which cooperate with the stationary dies 54-54 and 56-56, respectively, to sever the porous beads along a line substantially parallel to, and inwardly of, (Le, above) the porous bead-bearing edges of the walls 16, 18-18, and 22. The dies 54a-54a and 56a-56a, as shown, are secured to die holders 62 and 64 which are mounted on a horizontally movable plate 66, inwardly of the downwardly extending walls 16, 18-18, and 22. The plate 66 acts to successively move the dies 54a-54a and 56a-56a in a horizontal plane, in four directions, outwardly from the inner side of each of the walls 16, 18-18, and 22, to sever, as indicated, each wall along a line substantially parallel to, and inwardly of, each porous bead on the edges of the walls. As a result, a new edge is formed on each of the walls 16, 18-18, and 22 having small, easily removed burrs therealong adjacent to the outer surface of each of the said walls. The severing of the porous bead from each of the walls, as stated, is achieved without the need for changing the position of the die casting. Following removal of the porous beads, the die casting is released from its clamped position, and the outer surfaces of the walls 16, 18-18, and 22 are buffed to simultaneously impart a finish to the surfaces and to remove the burrs from the newly formed edges of the walls. The die casting is then ready to be plated.

Referring, now, to FIGS. 5, 6 and 7 of the drawings, a die casting 70, corresponding to the die casting 10, is shown as it appears after it is removed from the mold. Like the casting 10, the die casting 70 has a body 72 comprising a stepped front wall 74 formed of a raised, control knob-receiving section 740 and a depressed name plate section 74b. The body 72, similarly, has a rearwardly extending top wall 76 and a pair of rearwardly extending end walls 78-78. A longitudinally grooved pedestal portion 80 is joined to the body porof the body 72, and the bottom wall 82 of the pedestal portion 80 still have flashing 76a, 78a-78a, and 82a, respectively, joined thereto and extending outwardly therefrom in substantially the same plane. The die cast- I ing 70 further differs from the die casting in that no slots or openings have been formed in the section 74a of the front wall 74 thereof.

In FIGS. 6 and 7 of the drawings, the utilization of the method of this invention to remove the flashing from the die casting 70 while at the same time forming slots and openings in the section 74a of the front wall 74 is shown. As in the case of the die casting 10, the die casting 70 is cradled or supported on a support unit or locator body 90, the upper surface of which is shaped to conform to the contours of the underside of the front wall 74. The support unit or locator body 90, which includes female punching dies at the points where holes and slots are to be formed in the section 74a of the front wall 74, in turn, is supported on a stationary table 92. As with the die casting 10, the flashing-bearing edges of the top wall 76, the end walls 78-78, and the bottom wall 82 extend below the base of the table 92.

. A suitably contoured pressure communicating holder member 94 is supported on the outer or top surface of the frontwall 74. A vertically movable ram or head assembly 96 is employed both to'pierce slots and openings in the section 743. of the front wall 74, and to clamp the die casting 70 in a stationary position during removal of the flashing-bearing edges of the walls 76, 78-78, and 82.

The assembly 96, asshown, comprises a mounting plate 98 on which two pairs of shearing or cutting die holders 100-100 and 102-102 are mounted. Two pairs of stationary metal shearing or cutting holes 104-104 and 106-106 are secured to the holders in the same manner as described above with regard to the dies 54-54 and 56-56. The underside of the plate 98 has stops 108 secured to it for exerting pressure on the holder member 94 when the assembly is in its lowered or downstroke position. Also secured to the underside plate 98 are piercing punching dies. As shown, the punching die 1 10 forms the hole 28 (see FIG. 2) for the shaft of the control knob of the laundry unit, while the punching dies 112, 1 14 and 116 form the holes and the slots, respectively, corresponding to the holes 26 and 30, and the slots 24 in the die casting 10. The holes and slots, of course, are formed simultaneously when the assembly 96 is lowered.

As in the case of the removal of the porous beads from the edges of the walls of the die casting 10, the flashing is removed from the walls of the die casting 70 by means of two pairs of movable shearing or cutting dies 104a-l04a and 106a-l06a which cooperate with the stationary dies 104-104 and 106-106, respectively, to sever the flashing along a line substantially parallel to, and inwardly of, or above, the flashing-bearing edges of the walls 76, 78-78, and82. The dies 10411-10411 and 106a-106a are secured to die holders 118 and 120 which are mounted on a horizontally movable plate 122, inwardly of the walls 76, 78-78 and 82. As before, the plate 122 acts to successively move the dies 104a-l04a and 106a-106a, in

a horizontal plane, in four directions, outwardly from the inner side of each of the walls 76, 78-78 and 82, to sever eachwall along a line substantially parallel to, and inwardly of, or above, each flashing-bearing edge to form a new edgejof each wall having small, easily removed burrs therealong. The piercing or punching of the holes in the section 74a of the front wall 74 of the die casting and the severing of the flashing is achieved without the need for changing the position of the die casting 70. The assembly 96 acts to securely clamp the die casting 70 in position after it completes its downward, hole-and slot-forming'stroke. The holder member 94, the female dies the locator body 90, the table 92, the die holders 118 and 120, and the movable plate 122 are provided with registering bores 94a, a, 92a, 118a, a and 122a for removal of the slugs 124 punched from the front wall 74 by the punching dies 110, 112, 114 and 116.

After the flashing-bearing edges have been severed from the walls of the die casting 70, it is released from its clamped position, and, as with the die casting 10, the outer surfaces of the walls thereof are bufi'ed to prepare the surface for plating and to remove the small burrs from the newly formed edges of the walls 76, 78-78 and 82.

While the method of the present invention has been described with relation to its use in making a finished die casting of the type shown in FIGS. 2 and 5 of the drawings, it should be understood that the method can be used with die castings of substantially any shape and size. It should also be understood that various modifications and variations of the method and the means for carrying it out can be made without departing from the spirit and scope of the novel concepts disclosed herein.

What is claimed is:

1. A method of making a finished metal die casting having a wall portion, the outer surface of which is to be buffed, comprising: stationarily positioning with support means a metal die casting, from which unwanted metal is to be removed from an edge of the wall portion thereof, with the outer surface of the wall portion of the die casting facing outwardly with relation to the support means and said edge of the wall portion of the die casting extending to a point where it is free of contact with the support means, severing the wall portion at a point inwardly of the said edge thereof by moving metal cutting means'outwardly from the inner side of the wall portion to provide a new edge on the wall portion having metal burrs therealong adjacent to the outer surface of the wall portion, and buffing the outer surface of the wall portion to simultaneously impart a finished appearance to the surface and to remove the burrs from the newly formed edge.

2. A method according to claim 1 wherein said unwanted metal to be removed from the die casting comprises a porous beaded edge extending along the wall portion at the outer surface thereof.

3. A method according to claim 1 wherein said unwanted metal to be removed from the die casting comprises an edge of the wall portion having flashing extending outwardly therefrom at the outer surface of the wall portion.

4. A method of making a finished metal die casting having a wall portion, the outer surface of which is to be buffed, and in which one or more holes are to be formed, comprising: stationarily positioning with support means a metal die casting, in which one or more holes are to be formed and from which unwanted metal is to be removed from an edge of a wall portion thereof, with the outer surface of the wall portion of the die casting facing outwardly with relation to the support means and said edge of the wall portion of the die casting extending to a point where it is free of contact with the support means, bringing hole forming clamping means into contact with the die casting to form one or more holes therein, said clamping means cooperating with the support means to clamp the die casting therebetween, severing the wall portion at a point inwardly of the said edge thereof while the die casting is thusly clamped by moving metal cutting means outwardly wall portion.

II! t t 

1. A method of making a finished metal die casting having a wall portion, the outer surface of which is to be buffed, comprising: stationarily positioning with support means a metal die casting, from which unwanted metal is to be removed from an edge of the wall portion thereof, with the outer surface of the wall portion of the die casting facing outwardly with relation to the support means and said edge of the wall portion of the die casting extending to a point where it is free of contact with the support means, severing the wall portion at a point inwardly of the said edge thereof by moving metal cutting means outwardly from the inner side of the wall portion to provide a new edge on the wall portion having metal burrs therealong adjacent to the outer surface of the wall portion, and buffing the outer surface of the wall portion to simultaneously impart a finished appearance to the surface and to remove the burrs from the newly formed edge.
 2. A method according to claim 1 wherein said unwanted metal to be removed from the die casting comprises a porous beaded edge extending along the wall portion at the outer surface thereof.
 3. A method according to claim 1 wherein said unwanted metal to be removed from the die casting comprises an edge of the wall portion having flashing extending outwardly therefrom at the outer surface of the wall portion.
 4. A method of making a finished metal die casting having a wall portion, the outer surface of which is to be buffed, and in which one or more holes are to be formed, comprising: stationarily positioning with support means a metal die casting, in which one or more holes are to be formed and from which unwanted metal is to be removed from an edge of a wall portion thereof, with the outer surface of the wall portion of the die casting facing outwardly with relation to the support means and said edge of the wall portion of the die casting extending to a point where it is free of contact with the support means, bringing hole forming clamping means into contact with the die casting to form one or more holes therein, said clamping means cooperating with the support means to clamp the die casting therebetween, severing the wall portion at a point inwardly of the said edge thereof while the die casting is thusly clamped by moving metal cutTing means outwardly from the inner side of the wall portion to provide a new edge on the wall portion having metal burrs threrealong adjacent to the outer surface of the wall portion, and buffing the outer surface of the wall portion to simultaneously impart a finished appearance to the surface and to remove the burrs from the newly formed edge.
 5. A method according to claim 4 wherein the unwanted metal to be removed from the die casting comprises an edge of the wall portion having flashing extending outwardly therefrom at the outer surface of the wall portion. 